Study: Skin altered into blood cells

by Eryn Brown - Nov. 8, 2010 12:00 AMLos Angeles Times

Canadian scientists have turned human skin cells directly into blood cells, the first time one kind of mature human cell has been converted into another, according to a study published Sunday in the journal Nature.

The transformation was completed without first rewinding the skin cells into the flexible pluripotent stem cells that have most frequently been used to grow tissues. By skipping the pluripotent step, the researchers believe they have skirted the risk that the replacement cells might form dangerous tumors.

The team created blood progenitor cells - the mother cells that multiply to produce other blood cells - as well as mature blood cells, according to the report. Both types of cells could be useful in medical treatments, said study leader Mick Bhatia, a stem-cell scientist at McMaster University in Hamilton, Ontario.

"There is a great need for alternative sources of human blood," Bhatia said. "Since this source would come from a patient's own skin, there would be no concern of rejection of the transplanted cells."

The scientists used a trial-and-error approach to figure out which genes needed to be activated to reprogram the cells into blood cells. Then, they looked for the right combination of growth factors - blood proteins that promote development of the new cells - to coax the process along.

They found that they needed to turn on a single gene - called OCT4 - in the skin cells, and that the cells needed to bathe in precisely calibrated combinations of four to six growth factors, Bhatia said.

By tweaking the formula, the team was able to produce different types of blood cells, he said. For example, when they left out the protein called erythropoietin, the skin cells generated neutrophils and macrophages - types of white blood cell used by the immune system.

They tested the cells in mice to see if they would generate cancer.

They did not. But it is not yet clear whether the blood cells generated directly from skin will pose safety concerns of their own.